Boiling effects on trace element and sulfur isotope compositions of sulfides in shallow-marine hydrothermal systems: Evidence from Milos Island, Greece

Schaarschmidt A, Haase K, Klemd R, Keith M, Voudouris PC, Alfieris D, Strauss H, Wiedenbeck M (2021)

Publication Type: Journal article, Original article

Publication year: 2021

Journal

Original Authors: Anna Schaarschmidt, Karsten M. Haase, Reiner Klemd, Manuel Keith, Panagiotis C. Voudouris, Dimitrios Alfieris, Harald Strauss, Michael Wiedenbeck

Book Volume: 583

Pages Range: 120457

Article Number: 120457

DOI: 10.1016/j.chemgeo.2021.120457

Abstract

Boiling is a crucial process triggering ore formation in magmatic-hydrothermal systems and controlling the enrichment of precious and rare metal(loid)s in epithermal-porphyry mineralizations. Steep physicochemical gradients during boiling of hydrothermal fluids at shallow water depths caused metal(loid) precipitation along a 3 km long Pb-Zn-Ag vein system on Milos Island in the South Aegean Volcanic Arc. We present new trace element and Pb, Sr, and S isotope data from sulfides providing insights into the diversity of mineralization processes in shallow-marine hydrothermal systems. Lead and Sr isotope compositions of sulfides and sulfates reflect the mixing of fluids that reacted with metamorphic basement and the volcanic host rocks, whereas some of the S were derived from seawater. Investigation of mineralized samples along the Kondaros-Vani fault zone revealed distinct chemical variations that represent a vertical profile through the boiling zone of a hydrothermal system. Boiling during fluid ascent at decreasing temperatures (230–150 °C) and sulfur fugacities triggered the precipitation of sulfides rich in Zn, Pb, Fe, Cu, Ag, Sb, and As, resulting in increasing Pb, Ag, and Sb contents with decreasing depth. A pyrite group with high Tl/Cu and low As/Sb ratios, as well as δ34SVCDT values reaching as low as −6‰, is interpreted as precipitating from high-Cl liquids that underwent vigorous boiling at deeper crustal levels subsequent to tectonic faulting. Condensation of vapor (high Hg, Bi, and As contents) and mixing with seawater (high Mo contents) in the shallow-marine subseafloor sequences at Vani caused Hg-Bi-Mo-As-rich mineralization similar to the active hydrothermal system at Milos.

Authors with CRIS profile

Involved external institutions

Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum - GFZ Germany (DE) Westfälische Wilhelms-Universität (WWU) Münster Germany (DE) National and Kapodistrian University of Athens Greece (GR)

How to cite

APA:

Schaarschmidt, A., Haase, K., Klemd, R., Keith, M., Voudouris, P.C., Alfieris, D.,... Wiedenbeck, M. (2021). Boiling effects on trace element and sulfur isotope compositions of sulfides in shallow-marine hydrothermal systems: Evidence from Milos Island, Greece. Chemical Geology, 583, 120457. https://dx.doi.org/10.1016/j.chemgeo.2021.120457

MLA:

Schaarschmidt, Anna, et al. "Boiling effects on trace element and sulfur isotope compositions of sulfides in shallow-marine hydrothermal systems: Evidence from Milos Island, Greece." Chemical Geology 583 (2021): 120457.

BibTeX: Download